1. Field of the Invention
This invention relates to a switch apparatus for rotating and stopping a DC motor for opening and closing windows of a vehicle such as an automobile, for example, or DC motors used for similar applications. More particularly, the invention relates to a switch apparatus that will be used appropriately for a DC motor operating at a high power source voltage (in a 42 V electric system, for example).
2. Description of the Related Art
Prior Art: Re: 42 V Electric System
Existing automobiles have employed a 14 V electric system. As the number of electronic appliances mounted to the automobiles has increased, however, it,has become more difficult for the 14 V electric system to meet required power consumption. To solve this problem, an industry-university cooperation consortium has reached after intensive global discussion the consensus that a threefold higher voltage system, that is, “42 V system”, be employed in view of safety to the human body, and so forth.
[Prior Art as the Base: First Prior Art]
Electric equipment operating in the 42 V electric system includes a DC motor for opening and closing windows, assembled inside doors (so-called “DC motor for driving power windows”), for example.
FIG. 10 of the accompanying drawings is a structural view FIG. 10A of a prior art switch apparatus for rotating (normally and reversely) and stopping the DC motor for opening and closing the windows and its circuit diagram FIG. 10B (refer to non-patent reference 1, for example).
This switch apparatus 100 is fitted to each armrest installed inside a door of a front seat or a rear seat of the automobile. The state of the switch apparatus 100 shown in the drawing represents the state where a DC motor for driving power windows (hereinafter called “DC motor”) 101 is at halt. In other words, this state represents the one where a passenger inside the automobile does not operate a knob 102. This state will be hereinafter called “neutral state”.
The knob 102 is fitted to a case 103 on the door side in such a fashion as to be capable of turning by a predetermined angle both clockwise and counter-clockwise in the drawing. When the knob 102 is turned clockwise, the window is closed (hereinafter called “UP state”) and when it is turned counter-clockwise, the window is opened (hereinafter called “DOWN state”). When the operating force applied to the knob 102 is released (or a finger is released), a spring 104 and a plunger 105 buried into the knob 102 return the knob 102 to the neutral state and keep thereafter this neutral state.
A lower protuberance 106 of the knob 102 extending inside the case 103 exists at the position shown in the drawing when the knob 102 is under the neutral state. When the knob 102 is brought into the UP state, however, the lower protuberance 106 rocks to the left in the drawing (see FIG. 12A). When the knob 102 is brought into the DOWN state, the lower protuberance 106 rocks to the right in the drawing (not shown in the drawing).
A switch unit 108 mounted to a printed substrate 107 is provided inside the case 103. This switch unit 108 operates as a momentary type “2-circuit 4-contact type” switch and its appearance Is shown in FIG. 11. The switch unit 108 includes two common terminals 110 and 111 extended from one of the side surfaces of a casing 109, one normally-open terminal 112 extended from the other side surface of the casing 109 and two normally-closed terminals 113 and 114 extended from the bottom surface of the casing 109. These terminals 110 to 114 are soldered to a necessary conduction circuit formed on the printed substrate 107 and are electrically connected to a power source line (hereinafter called “+B line”) 115, a ground line 116 and a DC motor 101 to thereby accomplish the circuit diagram shown in FIG. 10B.
Switches A and B of two circuits are mounted inside the switch unit 108 as shown in FIG. 10(b). These switches A and B are exclusively switched in accordance with a slide position of a slider 117 that is fitted to the upper surface of the switch unit 108. Incidentally, the term “exclusive switching” hereby used means that only an NC (normally-closed) contact of either one of the switches A and B is opened. (In other words, only an NO (normally-open) contact of that switch is closed).
More concretely, when the slider 117 exists at the position shown in the drawing (under the neutral state), connection between a moving contact 118 of the switch A and the NC contact 122 and connection between a moving contact 119 of the switch B and an NC contact 123 are closed. At this position the NO contacts 120 and 121 and the NC contacts 122 and 123 of the two sets of the switches A and B are under the literal state (NO→normally open, NC→normally closed). When the slider 117 moves in a direction indicated by a leftward arrow L (hereinafter merely called “L direction”) in FIG. 11A (under the “UP state”), the closed state between the moving contact 119 of the switch B and the NC contact 123 is kept, the closed state of the NC contact 122 of the switch A is released and connection between the moving contact 118 and the NO contact 120 is afresh closed. Further, when the slider 117 moves in a direction indicated by a rightward arrow R (hereinafter merely called “R direction) (under the “DOWN state”) in FIG. 11A, the closed state between the moving contact 118 of the switch A and the contact 122 is kept, the closed state of the NC contact 123 of the switch B is released and connection between the moving contact 119 and the NO contact 121 is afresh closed.
Such a switching operation is brought forth by the operation of the slider 117 and by the lower surface shape of the slider 117. FIG. 11C is a sectional view of the slider 117 along a line X—X and FIG. 11D is a sectional view of the slider 117 along a line Y—Y. The X—X sectional part of the slider 117 is formed to an increased thickness at its right half portion and the Y—Y sectional part of the slider 117 is formed to an increased thickness at its left half portion. The switches A and B are exclusively switched in accordance with the positional relationship of these increased thickness portions as will become more apparent from the following explanation.
Incidentally, FIG. 10A depicts only one of the common terminals 110 and 111 and only one of the normally-closed terminals 113 and 114, for example. This is because each terminal is aligned back and forth and the rear terminal is hidden by the front terminal and cannot be observed.
The switch unit 108 operates as the momentary type “2-circuit 4-contact type” switch as explained already. In other words, the moving contacts 118 and 119, the NO contacts 120 and 121 and the NC contacts 122 and 123 are connected to the common terminals 110 and 111, the normally-open contact 112 and the normally-closed contacts 113 and 114, respectively. In this way, contact switching (switching of the moving contact 118 and the NO contact 120 and the NC contact 122 and switching of the moving contact 119 and the NO contact 121 and the NC contact 123) of the two circuits can be carried out exclusively.
Each of the moving contacts 118 and 119 is fitted to the distal end of each metal leaf spring type moving plate 124, 125. Push buttons 126A and 126B (push button 126A is for the switch A and the push button 126B is for the switch B) urge these metal leaf spring type moving plates 124 and 125 downward in the drawing.
The push buttons 126A and 126B keep contact with a lower surface of the slider 117 (see FIG. 11) capable of moving in the transverse direction in the drawing. One of the push buttons 126A is pushed down along the lower surface shape (X—X section increased thickness part: see FIG. 11C) with the movement of the slider 117 to the left (L direction) in the drawing as shown in FIG. 12A. The other push buttons 126B is pushed down along the lower surface shape of the slider 117 (Y—Y section increased thickness part: see FIG. 11D) with the movement of the slider 117 to the right (R direction) in the drawing.
An upper surface protuberance 127 of the slider 117 engages with the distal end of the lower protuberance 106 of the knob 102. The slider 117 slides to the right and left in the drawing (L-R direction) while following the rocking motion of the lower protuberance 106 of the knob 102 (UP state and DOWN state).
Therefore, when the knob 102 is pulled up and brought into the UP state in this switch apparatus 100, the slider 117 slides in the L direction and the push button 126A keeping contact with the X—X section increased thickness part of the slider 117 moves down. In consequence, connection between the moving contact 118 of the switch A and the NC contact 122 is opened and connection between the moving contact 118 of the switch A and the NO contact 120 is closed. When a finger is released from the knob 102 to attain the neutral state, the slider 117 returns to its original position, the push button 126A moves up and connection between the moving contact 11,8 of the switch A and the NC contact 122 is closed.
When the knob 102 is pushed down to attain the DOWN state, the slider 117 slides in the R direction and the push button 126B keeping contact with the Y—Y section increased thickness part of the slider 117 moves down, so that connection between the moving contact 119 of the switch B and the NC contact 123 is opened while connection between the moving contact 119 of the switch B and the NO contact 121 is closed. When the finger is released from the knob 102 to attain the neutral state, the slider 117 returns to its original position, the push button 126B moves up and connection between the moving contact 119 of the switch B and the NC contact 123 is closed.
When the knob 102 is under the neutral state in the circuit diagram shown in FIG. 10B, each contact of the switches A and B is under the state shown in the drawing. In other words, connection between the moving contact 118 of the switch A and the NC contact 122 is closed and connection between the moving contact 119 of the switch B and the NC contact 123 is closed. Under this state, connection between the DC motor 101 and the +B line 115 is cut off and a potential (negative plate side power source) of the ground line 116 is applied to the two driving inputs of the DC motor. Consequently, the DC motor 101 is at halt. This rotation stop state will be hereinafter called motor stop mode”.
In the circuit diagram shown in FIG. 12B, on the other hand, when the knob 102 is under the UP state, each contact of the switches A and B is under the state shown in the drawing. In other words, connection between the moving contact 118 of the switch A and the NO contact 120 is closed and connection between the moving contact 119 of the switch B and the NC contact 123 is closed. Under this state, a closed circuit of the +B line 115→NO contact 120→moving contact 118→DC motor 101→moving contact 119→NC contact 123→ground line 116 is formed. In consequence, the DC motor 101 rotates in the direction that closes the windows. This rotation direction is regarded as the normal rotation direction and the rotation state will be hereinafter called “motor normal rotation mode”.
Though not shown in the drawing, when the knob 102 is under the DOWN state, connection between the moving contact 118 of the switch A and the NC contact 122 is closed and connection between the moving contact 119 of the switch B and the NO contact 121 is closed. Under this state, a closed circuit of the +B line 115→NO contact 121→moving contact 119→DC motor 101→moving contact 118→NC contact 122→ground line 116 is formed. In consequence, the DC motor 101 rotates in the direction that opens the windows. This rotation direction is regarded as the reverse rotation direction and the rotation state will be hereinafter called “motor reverse rotation mode”.
Therefore, the switches A and B of the switch unit 108 can acquire the “motor stop mode” by applying the negative plate side power source (potential of the ground line 116) to each of one and other side driving inputs of the DC motor 101 and bringing the DC motor 101 into the stop state, the “motor normal rotation mode” by applying the positive plate side power source (potential of the +B line 115) to one side driving input of the DC motor 101 and the negative plate side power source (potential of the ground line 116) to the other side driving input and bringing the DC motor 101 to the normal rotation state, and the “motor reverse rotation mode” by applying the negative plate side power source (potential of the ground line 116) to one side driving input of the DC motor 101 and the positive side power source (potential of the +B line 115) to the other side driving input and bringing the DC motor 101 to the reverse rotation state.
The explanation given above represents the example where the rotation of the DC motor 101 is controlled by use of one switch unit 108. However, switch apparatuses of other types that can open and close the windows of the other seats (front and rear seats other than the driver's seat) are available depending on models of the automobiles.
FIG. 13 is its circuit diagram (refer to the non-patent reference 1. for example). This circuit includes in combination a switch unit 108 for the driver's seat and a switch unit 108′ for another seat and can rotate and stop the DC motor 101 (DC motor for opening and closing the window of another seat) not only from another seat but also from the driver's seat.
In the explanation given above, one each terminal (common terminal 110, 111 and normally-closed terminal 113, 114) is allocated to the moving contact 118, 119 and to the NC contact 122, 123 and one terminal (normally-open terminal 112) is allocated to the NO contact 120, 121. (In other words, the switch apparatus has five terminals in total). However, for example, as shown in FIG. 14, this arrangement is not restrictive and a type (having four terminals in total) is also known in which contacts connected to the ground line 116 (NC contacts 122 and 123 of the switches A and B) are wired to one another inside the unit and are extended from one terminal 114a and connected to the ground line 116. Alternatively, there is known another type having one circuit for a switch mechanism and two such circuits are arranged and used. In this case, the switch unit has six terminals in total.
[Problems of First Prior Art]
The prior art switch apparatus (shown in FIGS. 10 to 14) explained above operates normally without problems when it is applied to the original 14 V electric system. When the switch apparatus is applied to an electric system having a higher voltage such as the 42V electric system, however, a large current flows through the contacts connected to the negative plate power source during the return from the UP state to the neutral state or during the return from the DOWN state to the neutral state, and imparts damage to the contacts.
FIG. 15 is an explanatory view of this contact damage, wherein FIG. 15A presets the UP state, FIG. 15B represents the state “immediately before” the return to the neutral state and FIG. 15C represents the return to the neutral state. The difference from the explanation of the prior art given above resides in that a higher voltage (power source voltage of the 42 V electric system; hereinafter called “42 V”) is applied to the +B line 115.
Under the UP state as shown in FIG. 15A, connection between the NO contact 120 of the switch A and the moving contact 118 is closed and connection between the moving contact 119 of the switch B and the NC contact 123 is closed. Therefore, a closed circuit of the +B line 115→NO contact 120→moving contact 118→DC motor 101→moving contact 119→NC contact 123→ground line 116 is formed. In consequence, the DC motor 101 rotates in the direction that closes the windows. Next, as shown in FIG. 15B, when the finger is released from the knob 102, the close state between the NO contact 120 of the switch A and the moving contact 118 is released and the moving contact 118 starts moving towards the NC contact 122 while creating arc discharge 128 within an allowable range between it and the NO contact 120. Finally, connection between the moving contact 118 of the switch A and the NC contact 122 is closed as shown in FIG. 15C, the supply of the power source voltage to the DC motor 101 is cut off and the DC motor 101 comes to halt.
When the switch unit 108 of the prior art is employed, the contact gap is as small as about 0.5 mm and an arc discharge voltage for 42 V cannot be secured. Therefore, the moving contact 118 in which a voltage of several voltages remains applied is connected to the NC contact 122. According to the experiments carried out by the inventors of this application, a large current 129 (100 A or more) flows this time from the moving contact 118 to the ground line 116 through the NC contact 122 within a short time (about 0.5 ms) and a large discharge phenomenon (hereinafter called “dead short-circuit”) 130 develops between the NO contact 120 and the NC contact 122 and imparts damage (contact damage or contact destruction) to the moving contact 118 of the switch A and to the NC contact 122. This dead short-circuit 130 is likely to develop particularly in a range of an extremely quicker contact opening/closing speed (1,000 mm/s or more) than the ordinary contact opening/closing speed (100 to 400 mm/s).
Incidentally, to cope with the arc discharge, it is customary to enlarge the contact gap so as to correspond to the degree of the power source voltage. When the contact gap is enlarged (to about 4 mm, for example), the arc discharge voltage can be increased and the moving contact 118 can be connected to the NC contact 122 under the state where no voltage is applied to the moving contact 118 with the result that the contact damage can be avoided. According to this measure, however, the switch unit becomes drastically greater in scale and cannot be compactly mounted to the automobile.
[Improved Prior Art: Second Prior Art]
Therefore, the inventors of the invention have already proposed a “Switch Apparatus” (Japanese Patent Application No. 2002-256392, filed on Sep. 2, 2002) that improves the first prior art described above and does not invite the drastic increase of the scale of the switch unit even when applied to a higher power source voltage such as the 42 V electric system. This proposed technology is hereinafter called “second prior art”.
FIG. 16 is a structural view showing principal portions of a switch apparatus 200 according to the second prior art.
The switch apparatus 200 can be broadly divided into two switch elements (hereinafter called “first switch element 201” and “second switch element 202”, respectively) and a switch operation element 203 for conducting switching operations of these two switch elements 201 and 202.
The explanation will be given on each element. The first switch element 201 has six fixed electrode 201a to 201f of flat sheet-like metal conductors inserted into a molding base, not shown (or shaped into a thin film) and two moving plates 201g and 201h. The six fixed electrodes 201a to 201f are made of a metal material having high conductivity and highly resistant to wear. Three electrodes are aligned into a set and each set is Juxtaposed with each other. The first set has the fixed electrodes 201a to 201c and the second set has the remaining fixed electrodes 201d to 201f. 
The fixed electrodes 201a to 201c of the first set are aligned in the order of the fixed electrode 201a, the fixed electrode 201b and the fixed electrode 201c from the right to the left in the drawing along an imaginary axis 204. The fixed electrodes 201d to 201f of the second set are aligned in the order of the fixed electrode 201d, the fixed electrode 201e and the fixed electrode 201f from the left to the right in the drawing along the imaginary axis 204.
A gap L2a between the fixed electrode 201b and the fixed electrode 201c is smaller than a gap Lla between the fixed electrode 201a and the fixed electrode 201b. Similarly, a gap L2b between the fixed electrode 201e and the fixed electrode 201f is smaller than a gap L1b between the fixed electrode 201d and the fixed electrode 201e. Here, L1a=L1b and L2a=L2b. 
The two moving plates 201g and 201h have a suitable shape so that they can slide on the fixed electrodes 201a to 201c of the first set and on the fixed electrodes 201d to 201f of the second set along the imaginary axis 204, respectively. For example, the two moving plates 201g and 201h have two curve protuberances 201g_1 and 201g—2 (201h_1 and 201h_2 in the moving plate 201h), and are made of a metal material having high conductivity and highly resistant to wear.
Springs 201i and 201j urge down the two moving plates 201g and 201h, respectively. This urging force pushes the two curve protuberances 201g_1 and 201g_2 (201h_1 and 201h_2 in the moving plate 201h) of the two moving plates 201g and 201h, respectively, onto the fixed electrodes 201a to 201c of the first set and onto the fixed electrodes 201d to 201f of the second set.
The gap between the two curve protuberances 201g_1 and 201g_2 (201h_1 and 201h_2 in the moving plate 201h) of the moving plates 201g and 201h is set to a gap greater than L1a (L1b) described above. More concretely, in the case of one of the moving plates 201g by way of example, the gap is set so that the moving plate 201g can come into contact with only both of the fixed electrodes 201a and 201b of the first set and can close connection between these metal conductors, and can come into contact with only both of the fixed electrodes 201b and 201c of the first set and can close connection between these metal conductors.
The two moving plates 201g and 201h can move to the right and left in the drawing along the imaginary axis 204 while keeping the parallel state shown in the drawing due to the operation of the switching operation element 203.
When the two moving plates 201g and 201h exist at the positions shown in the drawing (hereinafter called “neutral state”) in the first switch element 201 having such a construction, the two curve protuberances 201g_1 and 201g_2 of one of the moving plates 201g come into contact with both of the fixed electrodes 201b and 201c of the first set. Therefore, these conductors can be brought into the closed state. The curve protuberances 201h_1 and 201h_2 of the other moving plate 201h come into contact with both fixed electrodes 201e and 201f of the second set and these conductors can be closed. In other words, connection between the fixed electrodes 201a and 201b of the first set can be brought into the open state and connection between the fixed electrodes 201d and 201e of the second set can be brought into the open state.
When the moving plate 201g is moved to the right in the drawing from the neutral state, its curve protuberances 201g_1 and 201g_2 come into contact with both fixed electrodes 201a and 201b of the first set and these conductors can be brought into the closed state. In other words connection between the fixed electrodes 201b and 201c of the first set can be brought into the open state. At this time, the other moving plate 201h simultaneously moves from the neutral state to the right in the drawing, and its curve protuberances 201h_1 and 201h_2 keep the fixed electrodes 201f and 201e of the second set under the closed state.
Similarly, when the moving plate 201h is moved to the left in the drawing from the neutral state, its curve protuberances 201h_1 and 201h_2 come into contact with both fixed electrodes 201d and 201e of the second set and these conductors can be brought into the closed state. In other words, connection between the fixed electrodes 201e and 201f of the second set can be brought into the open state. At this time, the other moving plate 201g simultaneously moves from the neutral state to the left in the drawing, and the curve protuberances 201g_1 and 201g_2 of the moving plate 201g keep the fixed electrodes 201b and 201c of the first set under the closed state.
A C part at the lower left of the drawing represents the first switch element 201 by the circuit diagram. In this circuit diagram, the moving plates 201g and 201h and the fixed electrodes 201b and 201e form two moving contacts. The fixed electrodes 201a and 201d form the NO contacts, respectively, and the fixed electrodes 201c and 201f form the NC contacts, respectively.
When the moving plates 201g and 201h exist under the neutral state shown in the drawing, the NC contacts (201c, 201f) are under the closed state. When one of the moving plates 201g moves from the neutral state to the right along the imaginary axis 204, the NC contact (201c) is released from the closed state and the NO contact (201a) is brought into the closed state. When the other moving plate 201h moves to the left from the neutral state along the imaginary axis 204, the NC contact (201f) is released from the closed state and the NO contact (201d) is brought into the closed state.
In other words, this first switch element 201 operates as a “2-circuit 4-contact type” switch. When the centering positions of the moving plates 201g and 201h are set to the neutral state shown in the drawing through the operation of the switching operation element 203, two (201c, 201f) of the four fixed electrodes 201a, 201c, 201d and 201f positioned on both right and left sides operate as the NC (normally closed) contacts and the remaining two (201a, 201d) operate as the NO (normally-open) contacts.
Next, the second switch element 202 will be explained. The second switch element 202 is constituted by mounting two sets of switch mechanisms including the following members and having the same construction with each other onto the same base substrate (not shown) as that of the first switch element 201.
The second switch element 202 includes U-shaped members 202a and 202b implanted onto the base substrate described above, metal leaf spring type moving plates 202c and 202d each having one of the ends thereof held by the U-shaped member 202a, 202b, moving contacts 202e and 202f each being fitted to the other end of the metal leaf spring type moving plate 202c, 202d, inverted L-shaped members 202g and 202h implanted onto the base substrate, and fixed contacts 202i and 202j fitted to the downward ends of the inverted L-shaped members 202g and 202h, respectively.
A notch 202k, 202m is defined at a part of each metal leaf spring type moving plate 202c, 202d. The notches 202k and 202m are curved and butted against the U-shaped members 202a and 202b, respectively. Resiliency of the notches 202k and 202m always keeps the moving contacts 202e and 202f fitted to the other end under the contact state with the fixed contacts 202i and 202j (under the closed state), respectively. Therefore, the fixed contacts 202i and 202j operate as the NC (normally-closed) contacts.
When downward external force (exceeding resiliency of the notches 202k and 202m) is applied to the metal leaf spring type moving plates 202c and 202d through push buttons 202n and 202p disposed discretely, the distal end of each metal leaf spring type moving plate 202c, 202d lowers, so that the contact (closed state) between the moving contact 202e, 202f and the fixed contact 202i, 202j is released and the line between these contact is opened.
AD portion in FIG. 16 represents the second switch element 202 by a circuit diagram. In this circuit diagram, two moving contacts 202e and 202f are closed with respect to the fixed contacts (NC contacts) 202i and 202j, respectively. Assuming hereby that the downward external force is applied to one of the metal leaf spring type moving plates 202c, the closed state between the moving contact 202e and the fixed contact (NC contact) 202i is released and these contacts are open. Similarly, when the downward external force is applied to the other metal leaf spring type moving plate 202d, the closed state between the moving contact 202f and the fixed contact (NC contact) 202j is released and these contacts are open. Therefore, the second switch element 202 operates as a “2-cricuit 2-contact type” switch having a pair of NC contacts (202i and 202j).
Next, the switching operation element 203 will be explained. The switching operation element 203 indicated by dash line in the drawing has the following functions 1 to 4.
<Function 1>
When the operation input by the driver (such as the UP and DOWN operations of the knob 102 explained at the beginning) does not exist, the switching operation element 203 can keep the first and second switch elements 201 and 202 under the neutral state shown in the drawing.
<Function 2>
The switching operation element 203 can return the first and second switch elements 201 and 202 to the neutral state shown in the drawing immediately after the release of the operation input by the driver.
<Function 3>
The switching operation element 203 can move both moving plates 201g and 201h of the first switch element 201 from the neutral state shown in the drawing in one direction (to the left in the drawing, for example) along the imaginary axis 204 in response to one operation input (for example, UP operation) by the driver and at the same time, can open one of the NC contacts (fixed contact 202j, for example) of the second switch element 202.
<Function 4>
The switching operation element 203 can move both moving plates 201g and 201h of the first switch element 201 from the neutral state shown in the drawing in the other direction (to the right in the drawing, for example) along the imaginary axis 204 in response to another operation input (for example, DOWN operation) by the driver and at the same time, can open the other NC contact (fixed contact 202i, for example) of the second switch element 202.
FIGS. 17 and 18 are explanatory views useful for explaining the operations of the switching operation element 203. Referring to FIG. 17, the switch operation element 203 includes operation means 203a having a similar structure to the structure of the slider 117 in the switch apparatus of the first prior art. This operation means 203a slides in the transverse direction in the drawing (L-R direction) along the imaginary axis 204 (that is the same as the imaginary axis 204 in FIG. 16) while following the movement of the knob 102 (UP state⇄neutral state⇄DOWN state) in the switch apparatus of the first prior art.
When the operation means 203a moves (slides) in one direction (hereinafter called “L direction) along the imaginary axis 204, connection between the fixed contact 202j of the second switch element 202 and its moving contact 202f is first open and then both moving plates 201g and 201h of the first switch element 201 move from the neutral state shown in the drawing in the L direction along the imaginary axis 204, thereby closing connection between the fixed electrodes 201d and 201e. Furthermore, connection between the fixed contact 202j of the second switch element 202 and its moving contact 202f is closed, thereby accomplishing the opening direction rotation driving function of the DC motor for opening/closing the windows. Therefore, all these associated contacts (201h, 201d, 201e, 202f and 202j) unitarily constitute the UP side motor driving switch group (UP switch group).
When the operation means 203a moves (slides) in the other direction (hereinafter called “R direction”) along the imaginary axis 204, connection between the fixed contact 202i of the second switch element 202 and its moving contact 202e is first open and then both moving plates 201g and 201h of the first switch element 201 move from the neutral state shown in the drawing in the R direction along the imaginary axis 204, thereby closing connection between the fixed electrodes 201a and 201b. Furthermore, connection between the fixed contact 202i of the second switch element 202 and its moving contact 202e is closed, thereby accomplishing the closing direction rotation driving function of the DC motor for opening and closing the windows. Therefore, all these associated contacts (201g, 201a, 201b, 202e and 202i) unitarily constitute the DOWN side motor driving switch group (DOWN switch group).
FIG. 18 is an explanatory view useful for explaining the operations of one of the switch groups (UP switch group for convenience). The X—X section and the Y—Y section represent the sectional plane in FIG. 17. The first stroke represents the neutral state at the initial position. Under this neutral state, the moving plate 201h of the first switch element 201 is positioned between the fixed electrode 201e at the center and the fixed electrode 201f at the right end and closes connection between these electrodes. The push button 202p of the second switch element 202 is lifted up while engaging with the lower surface recess 203b of the operation means 203a. The metal leaf spring type moving plate 202d is not inverted downward and connection between the moving contact 202f fitted to the distal end of the metal leaf spring type moving plate 202d and its fixed contact 202j is closed.
When the operation shifts from this state to the UP state (when the operation means 203a is moved in the L direction), the moving plate 201h of the first switch element 201 keeps the position in the first stroke described above, that is, in between the fixed electrode 201e at the center and the fixed electrode 201f at the right end, and closes connection between these electrodes in the second stroke immediately after the shift to the UP state. However, the push button 202p of the second switch element 202 shifts from the lower surface recess 203b of the operation means 203a to the increased thickness portion and is pushed down. Since the metal leaf spring type moving plate 202d is bent downward in this instance, the closed state between the moving contact 202f fitted to the distal end of the metal leaf spring type moving plate 202d and its fixed contact 202j is released to the open state.
Next, the UP state further proceeds to the third stroke, the moving plate 201h of the first switch element 201 is positioned between the fixed electrode 201d at the left end and the fixed electrode 201e at the center, and closes these electrodes while bringing connection between the fixed electrode 201e at the center and the fixed electrode 201f at the right end into the open state. At this time, the push button 202p of the second switch element 202 still keeps its position at the increased thickness portion of the operation means 203a and the metal leaf spring type moving plate 202d keeps the downward inverted state. Therefore, connection between the moving contact 202f fitted to the distal end of the metal leaf spring type moving plate 202d and its fixed contact 202j is kept open.
When the UP state further proceeds to the final stroke (fourth stroke), the moving plate 201h of the first switch element 201 keeps the position in the third stroke, that is, between the fixed electrode 201d at the left end and the fixed electrode 201e at the center, and closes connection between these electrodes. However, the push button 202p of the second switch element 202 is lifted up while engaging with the lower surface recess 203c of the operation means 203a (recess adjacent to the lower surface recess 203b), the metal leaf spring type moving plate 202d returns to the horizontal state and connection between the moving contact 202f fitted to the distal end of the metal leaf spring type moving plate 202d and its fixed contact 202j is closed.
FIG. 19 is a circuit diagram of a rotation (normal rotation/reverse rotation)/stop system of a DC motor for opening and closing windows that is constituted by the application of the switch apparatus 200 of this prior art (second prior art). In the drawing, a +B line 115 is a positive plate side power source (+B line of an automobile electric system). A ground line 116 is a negative plate side power source (ground line of the system). The impressed voltage of the +B line 115 is higher than that of the 14 V electric system and is a voltage of a 42 V electric system (power source voltage; 42V), for example.
Referring to FIG. 19, FIG. 19A represents a circuit under the DOWN state, for example, FIG. 19D represents a circuit when the state returns from the DOWN state to the neutral state, and FIG. 19B and FIG. 19C represent circuits under a transient state between them. Under the DOWN state, each contact of first and second switch elements 201 and 202 is under the state corresponding to the fourth stroke in FIG. 18. In other words, connection between a moving plate (201g) of the first switch element 201 and an NO contact (201a) and connection between a moving plate (201h) and an NC contact (201f) are closed, and two NC contacts (202i, 202j) of the second switch element 202 are closed.
Therefore, the potential (+42 V) of the +B line 115 is applied to one side driving input of the DC motor 101 and the potential (0 V) of the ground line 116 is applied to the other side driving input of the DC motor 101. In consequence, the DC motor 101 rotates in one direction (in a window opening direction). When the DOWN state is released under this state, that is, when a finger is released from the knob 102 as described at the beginning, the state shifts to the state shown in FIG. 19B. Under this state, the contacts of the first switch element 201 remain as such but both of the two NC contacts (202i, 202j) of the second switch element 202 are opened, thereby cutting off connection between one side driving input of the DC motor 101 and the ground line 116.
Next, when the state shifts to the state shown in FIG. 19C, the two NC contacts (202i, 202j) of the second switch element 202 keep the open state, the closed state between the moving plate (201g) of the first switch element 201 and the NO contact (201a) is released and connection between the moving plate (201g) and the NC contact (201c) is closed. Finally, the state shifts to the state shown in FIG. 19D. Namely, both of the two NC contacts (202i, 202j) of the second switch element 202 are closed, the ground line 116 is connected to the one and other side driving inputs of the DC motor 101 and the rotation of the DC motor 101 stops.
As described above, the second prior art brings the second switch element 202 into the open state to cut off the route of the large current before, or simultaneously with, switching of the contacts of the first switch element 201. Therefore, the large current explained at the beginning (large current 129 in FIG. 15) does not flow and contact damage of the first switch element 201 can be avoided. Incidentally, because the NC contacts are added for two circuits, the width of the switch apparatus becomes somewhat greater. However, because the contact gap need not be increased, the switch apparatus 200 does not invite the drastic increase of the scale and deterioration of response performance. Furthermore, because the second switch element 202 is the NC contacts, the space of the NO contact can be utilized for increasing the contact gap.
[Non-Patent Reference 1]
“Toyota VITZ Wiring diagrams/SCP10 System (1999-1˜)”, Service Dept. Toyota Motors, Jan. 13, 1999, pp 3-38 to 3-39